Alight emitting diode (LED) is a semiconductor light emitting device able to emit light of various colors due to the recombination of electrons and electron holes at a junction between p-type and n-type semiconductor layers when current is applied thereto. Such a semiconductor light emitting device is advantageous over a filament-based light emitting device in that it has a relatively longer lifespan, lower power consumption, superior initial-operation characteristics, and the like, in comparison thereto. These factors have continually boosted demand for semiconductor light emitting devices. Notably of late, a great deal of attention has been drawn to group III nitride semiconductors that can emit light within a blue short light wavelength region.
Since the development of LEDs using nitride semiconductors, technical advances have broadened the range of applications thereof. Thus, many studies are being conducted to determine how to utilize nitride semiconductor devices in general lighting apparatuses and electrical lighting sources. Nitride light emitting devices have been used as components employed in low-current, low output mobile products. The range of applications of nitride light emitting devices has further broadened to encompass the field of high-current, high-output products.
Accordingly, research into improvements in light emitting efficiency and semiconductor light emitting device quality has been undertaken, and in particular, light emitting devices having various electrode structures have been developed in order to improve light output rates and reliability thereof.